Poor customer service

My mother has a cellphone contract with Vodacom, and she upgraded 11 months ago, thus the phone she currently has, is 11 months old. The phone stopped working, and it looks like the battery acid came out? She took it to the Vodacom where her contract is, and they said that the phone got wet (which it didn't) and that they are not going to replace the phone (even though it is still under warranty), alternatively they can try to fix the phone for her, and it will cost her R9000.

I feel this is unacceptable, and that they have to replace the phone.